Posted by: eric91

Hi, I think that the velocity of stepper motor is regulated only by stepper driver and software. Software have Maximum 2000steps/sec both at 24v and 50v. If you change volts or ampere, I think that change only the torque.

I think the better choice is to put  2 plastic gears between stepper Motor and flow valve. Is quite simple, the only problem can be the vibrations..

 

IMG_20180419_133723.jpg

Hi Eric , you are absolutely right about the software and ST-M5045 Micro-Stepping Stepper Motor Driver controlling the speed  ( PWM)  , I stand corrected and i am wrong. 

Nice pictures keep them coming. Pump valve =16 teeth/stepper_motor =32 teeth gearing ratio arrangement will be nice to see working and increasing the speed and halving the time factor in response.

What does the pump valve look like in shape and size , I'm just being curious here ?

Why are you using plastic gears ?

Bye

Hi, the valve is VRFB 90 1/2" hydraulic flow valve, is a precise flow regulation valve, although the first 4/5 turns are unuseless because doesnt give any load to engine. This afternoon I will place a photo of how I Connect the valve to stepper engine...

I will use plastic gears (pom) because the price is pretty good and also because the torque trasmitted is very low.

Posted by: eric91

Hi, the valve is VRFB 90 1/2" hydraulic flow valve, is a precise flow regulation valve, although the first 4/5 turns are unuseless because doesnt give any load to engine. This afternoon I will place a photo of how I Connect the valve to stepper engine...

I will use plastic gears (pom) because the price is pretty good and also because the torque trasmitted is very low.

Hi Eric , OK , plastic gears wear/strip very easy, that is my opinion . I have no idea what a VRFB 90 1/2" hydraulic flow valve looks like inside or outside , so you cannot load up the engine the first 4/5th of the turn of the valve handle.

Sounds like its either its on of its off and nothing in between with load ? OR am i misunderstanding what you mean by , " first 4/5 turns are unuseless" ??? 

Is the inside of the valve a ball valve straight through hole arrangement or a barrel that travels up and down or a sluice gate valve arrangement that allows the oil to flow through it? 

Some news about geared stepper engine... It's only to align gear shaft to hydraulic valve.... Transmission ratio 0.5..

.. 

Hi Eric , any new news how the speed is responding ?

What does the pump valve look like inside  shape and size , I'm just being curious here ???? VRFB 90 1/2" hydraulic flow valve ???

Posted by: Mach_1

Hi Eric , any new news how the speed is responding ?

What does the pump valve look like inside  shape and size , I'm just being curious here ???? VRFB 90 1/2" hydraulic flow valve ???

 

 

Hi mach, here  https://www.hydrapac.it/hydraulic-valves/flow-regulator-valves/90-flow-regulator-valves-vrfb-90 you can see in details what is a vrfb valve. Finally I have finish the gear on stepper engine but I dont have resolute my problems, I think I have to do some tests with differents value of kp and ki. Next days I will do some test with the support of jostein that is very kind and patient! My problem is that brake doesnt work correctly, also with manual control, but work fine only when I test it in brake setup page. 

Hi Eric , ok the  VRFB 90 1/2" hydraulic flow valve has a Poppet valve with a needle and seat arrangement inside it . Interesting drop curve for the valve Will be interesting once you run it again.

hi 

i am building a hydraulic dyno with a big pump - tyrone fpdv550  181.24 cc rev , i have this valve ffg2008ta  http://seawayfluidpowergroup.com/wp-content/themes/seawayfluidpowergroup/uploads/needle-valve-series.pdf

for a stepper motor is it better for me a nema 42  than a 34...?    i can have 10-20-or 30 nm ,1000 to 4000 oz-in

like this...?  https://www.automationtechnologiesinc.com/products-page/nema-42/nema42-stepper-motor-3256/

https://www.automationtechnologiesinc.com/products-page/kl-stepper-drivers/kl-11080-stepper-drive/

what do you think ?    i fear to not have enuff torque with a to small stepper choice  to turn my big valve and have very good

steady state rpm control with the pid

and Eric do you have some news...  or good control of your system ?

thanks

the pump

https://www.lifcohydraulics.com/pdfs/Tyrone-(FPDV25)-Dry-Valve-Pumps.pdf

Hi,

A few things to think about here:

• The control from min to max valve opening needs to be very fast, so do calculate the number of steps you need and max steps per sec (maybe 2000 steps/sec), and note that you need to include acceleration (maybe 5000 steps/sec^2). You may need gearing if it is not fast enough (at least sub 0.5 sec, preferably faster)
• 100% brake must NOT equal valve completely closed, or you will very abruptly stop the engine, even if the valve goes to 100% for just a fraction of a second. Adjust the min and max brake in software to avoid this.
• The valve should ideally provide a linear brake response. By that I mean if 25% brake gives you X newton meters of braking force, 50% brake should give 2X Nm braking force. This is not necessarily the case for your valve. If you don't achieve this, then the optimum PID parameters will not be the same for all valve openings, which means you will have to go for a conservative (= slow response) setting. You should take a look at flow vs valve opening at a fixed pressure for example, see if your valve is fairly linear. 

I was working with Eric over Facebook Messenger and we got the system to be very stable at 6000RPM, but it did not work well at 10000 RPM and above. It was also not stable on manual control at high RPMs. After some investigations it was found that the pump was way too small, and it could not cope with the high horsepower at higher RPMs. He is rebuilding with another pump.

Cheers,
Jostein

hi

thank you Jostein for your fast reply

my dyno is not completed  , i ask questions before i buy your dyno system , i have 2 valve if i need to...

i think the max in your software is 2000 steps/ sec  and if i need faster valve to open and closed i will need to have a reduction

like 2 to 1 or 3 to 1  like you tell me  , if i reduce my stepper motor to turn the valve faster i will drop in torque ...its my question about the need of a big stepper motor ?  my valve can be hard to open and close with the pressure and  i also think that my valve will not be 100 % linear...,  full open to full close is 7 turn

with 200 steps per turn its 1400 step

i also have a safety bypass valve that can open over 3000 psi and can flow 30 gal min , 120l min to not shock the system

i dont need very fast ramp run  , just some good steady state rpm to map fuel table and timing with out to much oscilation

or big rpm variation , and with your closed loop pid system i will not have to chase rpm manually if it drift..

thanks

Hi stepper dyno, Im just rebuilding the brake with 70cc pump instead of 30cc pump that Ii too small for My kart 125 Engine. After some tests, I have also broken the pump's bearing.

In My setup I use nema 34 stepper engine that has about 7Nm of torque. I have add also 0.5 Gear ratio, I think it's useful also for your setup. What kind of engine you will test? 

hi   Eric

thank you for your information

from 30cc to 70cc more than double your pump ,   i think you will be correct

i will test snowmobile engine

Hi guys, some updates of my hydraulic brake with 70cc gear pump and new chassis with 2 ucp 210 bearings for shaft and 2 ucp 209 bearings for pump. 

Other update is the motor support sled that now is hold at chassis by rubber's anti-vibration support.